Heat pump and method for calculating heating-medium flow rate of heat pump

ABSTRACT

A heating-medium flow rate is obtained with sufficient accuracy even if an inexpensive flow rate sensor is used. Provided is a turbo-refrigerator including an evaporator that cools or heats a heating medium flowing from an external load, a condenser that exchanges heat with outside air or cooling water, a coolant circulation path through which a coolant is circulated between the evaporator and the condenser, and a turbo-compressor provided in the coolant circulation path, the turbo-refrigerator comprising a differential pressure sensor that measures the differential pressure between the inlet-side pressure and the outlet-side pressure of cold water in the evaporator, and a control panel storing a loss factor of the evaporator and calculating the flow rate of the cold water in the evaporator on the basis of the loss factor and the differential pressure output from the differential pressure sensor, wherein the control panel performs control using the calculated flow rate of the cold water and transmits the flow rate of the cold water to facility-side equipment.

TECHNICAL FIELD

The present invention relates to a heat pump and a method forcalculating the heating-medium flow rate of a heat pump.

This application is based on Japanese Patent Application No.2010-002624, the content of which is incorporated herein by reference.

BACKGROUND ART

For example, a turbo-refrigerator is used to achieve zoned airconditioning or air conditioning of semiconductor manufacturingfacilities. FIG. 4 illustrates a block diagram of a heat source systemthat uses a conventional turbo-refrigerator. As shown in FIG. 4, aturbo-refrigerator 50 cools cold water (heating medium) supplied from anexternal load 51, such as an air conditioner and a fan coil, to apredetermined temperature and supplies the cooled cold water to theexternal load 51. A cold water pump 52 that pumps the cold water isdisposed upstream of the turbo-refrigerator 50, as viewed from coldwater flow. Furthermore, a cold water flowmeter 53 that measures theflow rate of cold water flowing out of the cold water pump 52 isprovided downstream of the cold water pump 52. The output of the coldwater flowmeter 53 is sent to a control unit (not shown) that controlsthe turbo-refrigerator 50, and this cold water flow rate is used as oneof the control parameters to control the turbo-refrigerator 50.

CITATION LIST Patent Literature

-   {PTL 1} Japanese Unexamined Patent Application, Publication No.    2009-204262

SUMMARY OF INVENTION Technical Problem

For example, in the heat source system described above, anelectromagnetic flowmeter is used as a cold water flowmeter thatmeasures the flow rate of cold water output from the turbo-refrigerator.However, electromagnetic flowmeters are so expensive that it issometimes difficult to adopt them.

Furthermore, a known method in the related art generally calculates theflow rate from a differential pressure using a differential pressuresensor, which is cheaper than the electromagnetic flowmeter. However,because the turbo-refrigerator tends to cause pressure fluctuations of aheating medium, such as cold water, application of a generaldifferential pressure sensor to the turbo-refrigerator has a problem inthat it is not possible to satisfy the required accuracy because oflarge variations in the measured value.

The present invention is made in consideration of such circumstances,and it is an object thereof to provide a heat pump and a method forcalculating the heating-medium flow rate of a heat pump, which iscapable of obtaining the heating-medium flow rate with sufficientaccuracy even if an inexpensive differential pressure sensor is used.

Solution to Problem

To solve the above problem, the present invention adopts the followingsolutions.

A first aspect of the present invention is a heat pump including a firstheat exchanger that cools or heats a heating medium flowing from anexternal load, a second heat exchanger that exchanges heat with outsideair or cooling water, a coolant circulation path through which a coolantis circulated between the first heat exchanger and the second heatexchanger, and a turbo-compressor provided in the coolant circulationpath, the heat pump comprising: a differential-pressure measuring partfor measuring the differential pressure between the inlet-side pressureand the outlet-side pressure of the heating medium in the first heatexchanger; and a control part storing a loss factor of the first heatexchanger, for calculating the flow rate of the heating medium in thefirst heat exchanger on the basis of the loss factor and thedifferential pressure output from the differential-pressure measuringpart, wherein the control part performs control using the flow rate ofthe heating medium and transmits the flow rate of the heating medium tofacility-side equipment.

With the above configuration, the differential pressure between theinlet-side pressure and the outlet-side pressure of the heating mediumin the first heat exchanger is measured using the differential pressuresensor, and the flow rate of the heating medium in the first heatexchanger is calculated using this measurement data and the loss factorunique to the first heat exchanger. Accordingly, a heating-medium flowrate that sufficiently satisfies the required accuracy can be obtainedwith an inexpensive, simple configuration.

In the heat pump described above, the control part may obtain acorrection term depending on the measurement delay time of theoutlet-side pressure according to the amount of the heating medium heldin the first heat exchanger and may correct the flow rate of the heatingmedium using the correction term.

Since the flow rate is corrected using the correction term depending onthe measurement delay time of the outlet-side pressure based on theamount of the heating medium held in the first heat exchanger, an errordue to the amount of the heating medium held in the first heat exchangercan be eliminated, and thus, the heating-medium-flow-rate calculationaccuracy can be improved.

In the heat pump described above, the control part may obtain thepermissible quantity of heat exchanged in the first heat exchanger bysubstituting the current motive power consumption of theturbo-compressor and the quantity of heat exchanged in the second heatexchanger into a relational expression expressing the relationship amongthe motive power consumption of the turbo-compressor, the quantity ofheat exchanged in the first heat exchanger, and the quantity of heatexchanged in the second heat exchanger and may determine the permissiblerange of the flow rate of the heating medium in the first heat exchangerfrom the permissible quantity of heat exchanged in the first heatexchanger, wherein if the flow rate of the heating medium determined bycalculation exceeds the flow rate range of the heating medium, thecontrol part may determine the flow rate of the heating medium on thebasis of the flow rate range of the heating medium and may transmit thevalue to the facility-side equipment.

With such a configuration, the control part stores a relationalexpression that is satisfied among the motive power consumption of theturbo-compressor, the quantity of heat exchanged in the first heatexchanger, and the quantity of heat exchanged in the second heatexchanger, and determines the permissible range of the heating-mediumflow rate of the first heat exchanger using this relational expression,and if the cold-water flow rate calculated on the basis of themeasurement data from the differential pressure sensor exceeds thepermissible range of the heating-medium flow rate, the control partdetermines the heating-medium flow rate of the first heat exchangerobtained from the relational expression and transmits this value to thefacility-side equipment.

Accordingly, this allows the reliability of the measurement data fromthe differential pressure sensor to be evaluated using the aboverelational expression, thus allowing a fault in the differentialpressure sensor to be detected. Furthermore, even if a fault in thedifferential pressure sensor is detected, because the heating-mediumflow rate obtained from the relational expression is transmitted to thefacility-side equipment, data transmission to facility-side equipmentcan continue.

A second aspect of the present invention is a method for calculating theheating-medium flow rate of a heat pump including a first heat exchangerthat cools or heats a heating medium flowing from an external load, asecond heat exchanger that exchanges heat with outside air or coolingwater, a coolant circulation path through which a coolant is circulatedbetween the first heat exchanger and the second heat exchanger, and aturbo-compressor provided in the coolant circulation path, wherein adifferential-pressure measuring part for measuring the differentialpressure between an inlet-side pressure and an outlet-side pressure areprovided at an inlet and an outlet of the heating medium of the firstheat exchanger, and the flow rate of the heating medium in the firstheat exchanger is calculated on the basis of the loss factor of thefirst heat exchanger and the differential pressure output from thedifferential-pressure measuring part.

Advantageous Effects of Invention

The present invention provides an advantage in that it is capable ofobtaining a heating-medium flow rate with sufficient accuracy even withan inexpensive, differential pressure sensor.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating, in outline, the configuration of aheat source system according to a first embodiment of the presentinvention.

FIG. 2 is a diagram illustrating, in outline, the configuration of aturbo-refrigerator according to the first embodiment of the presentinvention.

FIG. 3 is a diagram for explaining a case in which the cold-water flowrate is corrected on the basis of the amount of cold water held in anevaporator.

FIG. 4 is a diagram illustrating, in outline, the configuration of aconventional heat source system.

DESCRIPTION OF EMBODIMENTS First Embodiment

A heat pump according to a first embodiment of the present inventionwill be described hereinbelow using the drawings. Although thisembodiment is described using an example in which the heat pump is aturbo-refrigerator, it is not limited thereto. For example, instead ofthe turbo-refrigerator, it may be a chiller, an absorption refrigerator,etc.

FIG. 1 illustrates, in outline, the configuration of a heat sourcesystem 1 incorporating a turbo-refrigerator according to thisembodiment. The heat source system 1 is installed in, for example,buildings and plant facilities. As shown in FIG. 1, the heat sourcesystem 1 is equipped with three turbo-refrigerators 11 that cool andheat cold water (heating medium) to be supplied to an external load 3,such as an air conditioner or a fan coil. These turbo-refrigerators 11are disposed in parallel with the external load 3.

Cold water pumps 21 that pump cold water are disposed upstream of theindividual turbo-refrigerators 11, as viewed from the cold water flow.These cold water pumps 21 distribute the cold water from a return header32 to the individual turbo-refrigerators 11. The individual cold waterpumps 21 are each driven by an inverter motor, and the rotational speedsare changed, thus allowing for variable flow rate control.

A supply header 31 is configured to collect cold water obtained in theindividual turbo-refrigerators 11. The cold water collected in thesupply header 31 is supplied to the external load 3. The cold water thatis increased in temperature by being used for air conditioning or thelike in the external load 3 is distributed to the return header 32. Thecold water is separated in the return header 32 and is distributed tothe individual turbo-refrigerators 11.

Cold water pipes upstream of the individual turbo-refrigerators 11 areprovided with cold-water-inlet-temperature sensors 29 for measuring thetemperatures of cold water flowing into the individualturbo-refrigerators 11. The outputs of the cold-water-inlet-temperaturesensors 29 are individually sent to control panels 74 (see FIG. 2),described later, of the individual turbo-refrigerators 11. If a bypassvalve 34 of a bypass pipe 33 is fully open, a temperature sensor 29 bprovided at a cold water pipe upstream of the return header 32 may beused instead of the cold-water-inlet-temperature sensors.

FIG. 2 illustrates the detailed configuration of the turbo-refrigerator11.

The turbo-refrigerator 11 is configured to achieve a two-stagetwo-expansion subcooling cycle. This turbo-refrigerator 11 includes aturbo-compressor 60 that compresses a coolant, a condenser (second heatexchanger) 62 that condenses a high-temperature, high-pressure gascoolant compressed by the turbo-compressor 60, a subcooler 63 thatapplies supercooling to the liquid coolant condensed by the condenser62, a high-pressure expansion valve 64 that expands the liquid coolantfrom the subcooler 63, an intermediate cooler 67 that is connected tothe high-pressure expansion valve 64 and is connected to theintermediate stage of the turbo-compressor 60 and to the low-pressureexpansion valve 65, and an evaporator (first heat exchanger) 66 thatevaporates the liquid coolant expanded by the low-pressure expansionvalve 65.

The turbo-compressor 60 is a centrifugal two-stage compressor and isdriven by an electric motor 72 whose rotational speed is controlled byan inverter 70. The output of the inverter 70 is controlled by thecontrol panel 74. The turbo-compressor 60 may be a constant-speedcompressor having a constant rotational speed. A coolant inlet port ofthe turbo-compressor 60 is provided with an inlet guide vane(hereinafter referred to as “IGV”) 76 that controls the flow rate of anintake coolant to allow for capacity control of the turbo-refrigerator11.

The condenser 62 is provided with a condensed-coolant pressure sensor PCfor measuring the condensed coolant pressure. The output of the sensorPC is transmitted to the control panel 74.

The subcooler 63 is provided downstream of the coolant flow of thecondenser 62 so as to apply supercooling to the condensed coolant. Atemperature sensor Ts that measures the coolant temperature aftersupercooling is provided just behind the subcooler 63 at the coolantflow downstream side.

A cooling heat-transfer pipe 80 passes through the condenser 62 and thesubcooler 63 to cool them. The cooling-water flow rate is measured by aflowmeter F2, the cooling-water outlet temperature is measured by atemperature sensor Tcout, and the cooling-water inlet temperature ismeasured by a temperature sensor Tcin. The heat of the cooling water isexhausted to the outside by a cooling tower (not shown), and the coolingwater is thereafter introduced to the condenser 62 and the subcooler 63again.

The intermediate cooler 67 is provided with a pressure sensor PM formeasuring an intermediate pressure.

The cold water inlet and outlet of the evaporator 66 are provided withdifferential pressure sensors PEin and PEout, respectively, formeasuring the differential pressure between the inlet and outlet of thecold water. By absorbing heat in the evaporator 66, rated-temperature(for example, 7° C.) cold water can be obtained. A cold-water heattransfer pipe 82 for cooling the cold water to be supplied to theexternal load 3 passes through the evaporator 66. The cold-water outlettemperature is measured by a temperature sensor Tout, and the cold-waterinlet temperature is measured by a temperature sensor Tin.

A hot-gas bypass pipe 79 is provided between the vapor phase portion ofthe condenser 62 and the vapor phase portion of the evaporator 66.Furthermore, a hot-gas bypass valve 78 for controlling the flow rate ofa coolant flowing in the hot-gas bypass pipe 79 is provided. Adjustingthe hot-gas bypass flow rate with the hot-gas bypass valve 78 allows forcapacity control in a very small load region that cannot be sufficientlycontrolled by the IGV 76.

The turbo-refrigerator 11 shown in FIG. 2 is described when applied to acase in which the condenser 62 and the subcooler 63 are provided, inwhich heat is exchanged between the coolant and the cooling water whoseheat is exhausted to the outside in the cooling tower to thereby heatthe cooling water. Alternatively, for example, an air heat exchanger maybe provided instead of the condenser 62 and the subcooler 63, and heatmay be exchanged between the outside air and the coolant by the air heatexchanger.

The turbo-refrigerator 11 applied to this embodiment is not limited tothe turbo-refrigerator having only the cooling function described above;for example, it may have only a heating function or both a coolingfunction and a heating function. The medium whose heat is exchanged withthe coolant may be either water or air.

In FIG. 2, measurement data items obtained by the individual sensors aretransmitted to the control panel 74, in which various controls based onthese measurement data are performed.

Measurement of the flow rate of cold water in the evaporator 66, whichis a feature of the present invention, will be specifically described.

The control panel 74 stores a loss factor ζ of the evaporator 66 inadvance. The control panel 74 calculates a flow rate Q using thedifferential pressure ΔP and the loss factor ζ measured by thedifferential pressure sensors PEin and PEout in the following formula(1), where A is a cross-sectional area, ζ is a loss factor, ρ is thedensity of the heating medium, and v is a flow velocity.

$\begin{matrix}\left\{ {{Formula}\mspace{14mu} 1} \right\} & \; \\{{Q = {{\xi \sqrt{\Delta \; P}} = {\xi \sqrt{P_{in} - P_{out}}}}}{Q = {Av}}{{\Delta \; P} = {\zeta \frac{\rho \; v^{2}}{2g}}}{v = \sqrt{\frac{2g}{\rho\zeta}\Delta \; P}}{\xi = {A\sqrt{\frac{2g}{\rho\zeta}}}}} & (1)\end{matrix}$

The control panel 74 controls the turbo-refrigerator 11 on the basis ofthe various parameters, such as the flow rate Q, and transmits the flowrate Q and the various parameters to external facility-side equipmentvia a communication medium. The facility-side equipment monitors, forexample, the coefficient of performance (COP) etc. of theturbo-refrigerator 11 and uses the transmitted parameters for thesemonitored items.

With the turbo-refrigerator and the method for calculating theheating-medium flow rate of the turbo-refrigerator according to thisembodiment, as described above, since the differential pressure at thecold water outlet and inlet of the evaporator 66 is measured using thedifferential pressure sensors, and the flow rate of the cold water inthe evaporator 66 is calculated using this measurement data and the lossfactors ζ of the individual evaporators 66, a heating-medium flow ratethat sufficiently satisfies required accuracy can be obtained with aninexpensive, simple configuration.

The heating-medium flow rate Q of the evaporator 66 has temperaturedependency. Accordingly, the control panel 74 may calculate the flowrate Q using an operational expression that involves temperaturedependency, instead of Formula (1).

Furthermore, the measurement data transmitted from the above-describeddifferential pressure sensors includes disturbance due to, for example,opening/closing of the various valves provided on the coolantcirculation path of the turbo-refrigerators 11. To eliminate suchdisturbance, the heating-medium flow rate Q may be calculated from theabove Formula (1), for example, by processing sampling data measured bythe differential pressure sensors using the following expression (2) or(3) and using the processed data.

$\begin{matrix}\left\{ {{Formula}\mspace{14mu} 2} \right\} & \; \\{x_{ave} = \frac{{\Delta \; {T \cdot \left( {n - 1} \right) \cdot x_{{{ave} \cdot n} - 1}}} + {\Delta \; {T \cdot x}}}{\Delta \; {T \cdot n}}} & (2) \\{x_{ave} = \frac{{\Delta \; {T \cdot x_{{{ave} \cdot n} - 1}}} + {\Delta \; {T \cdot x}}}{T + {\Delta \; T}}} & (3)\end{matrix}$

Both expressions (2) and (3) above are operational expressions forcalculating a moving average, where xave is a differential pressure ΔPduring a predetermined period of time for which the moving average istaken, ΔT is a sampling period, n is the number of moving-average dataitems, and xave·n−1 is the moving average of the immediately precedingsampling data. By finding the heating-medium flow rate Q from Formula(I) using the moving-average differential pressure in this way,disturbance (noise) due to, for example, opening/closing of the valvesprovided in the refrigerating cycle of the turbo-refrigerator 11 can beeliminated, thus allowing a more accurate heating-medium flow rate Q tobe obtained.

Furthermore, the evaporator 66 in the turbo-refrigerator 11 holds alarge amount of water because of its large size. This causes a timedifference according to the amount of held water between the pressure atthe cold water inlet of the evaporator 66 and the pressure at the coldwater outlet. Accordingly, to eliminate an error in differentialpressure due to this time difference, a correction term based on theamount of water held in the evaporator 66 may be obtained, and the coldwater flow rate may be corrected using this correction term.

For example, as the temporal change in pressure, it is assumed that apressure P1(t) at the cold water inlet side of the evaporator 66increases at a constant rate of change, and a pressure P2(t) at the coldwater outlet side is constant, as shown in FIG. 3.

In this case, the flow rate Q [m3/sec] at that time can be expressed asthe following expression (4), where T is the present time.

{Formula 3}

Q=α√{square root over (ΔP)}  (4)

ΔP=P1(T)−P2(T)

On the other hand, if we let V [m3] be the amount of held water from thecold water inlet side to the cold water outlet side for which thedifferential pressure is measured, a flow rate Q′ [m3/sec] at a timepoint before the present time T to the time when the cold water reachesthe cold water outlet side from the cold water inlet side at the currentflow rate is expressed as the following expression (5).

$\begin{matrix}\left\{ {{Formula}\mspace{14mu} 4} \right\} & \; \\{{Q^{\prime} = {\alpha \sqrt{\Delta \; P^{\prime}}}}\begin{matrix}{{\Delta \; P^{\prime}} = {{P\; 1\left( {T - \frac{V}{Q}} \right)} - {P\; 2\left( {T - \frac{V}{Q}} \right)}}} \\{= {{P\; 1\left( {T - \frac{V}{Q}} \right)} - {P\; 2(T)}}}\end{matrix}} & (5)\end{matrix}$

Accordingly, by calculating the flow rate Q′ using a differentialpressure ΔP′ that takes the above time delay into consideration, theerror due to the amount of water held in the evaporator 66 can beeliminated, and thus, the cold-water-flow-rate calculation accuracy canbe improved.

Second Embodiment

Next, a turbo-refrigerator and a method for calculating theheating-medium flow rate of the turbo-refrigerator according to a secondembodiment of the present invention will be described.

In a turbo-refrigerators 11, the relational expression given by thefollowing expression (6) holds for the motive power consumption W of aturbo-compressor 60, the quantity of heat exchanged in an evaporator 66,Qe, and the quantity of heat exchanged in a condenser 62, Qc.

Qe=Qc−W  (6)

In general, the turbo-refrigerator is provided with a flowmeter F2 thatmeasures the flow rate of cooling water that flows into the condenser 62or flows out of the condenser 62, as shown in FIG. 2, and the flow rateof the cooling water is measured by the flowmeter F2, so that thequantity of heat exchanged in the condenser 62, Qc, can be calculatedfrom the cooling-water flow rate using the following expression (7).

Qc=Cp·ρ·qc·(Tcout−Tcin)  (7)

where cp is specific heat [kJ/(kg·K)], ρ is density [kg/m3], qc isvolumetric flow rate [m3/sec], Tcout is cooling-water outlet temperature[K], and Tcin is cooling-water inlet temperature [K].

The motive power consumption W is also constantly measured at thecontrol panel 74. Accordingly, the quantity of heat exchanged in theevaporator 66, Qe, can be found by using the quantity of heat exchangedin the condenser 62, Qc, obtained from the cooling-water flow rate andthe motive power consumption W in the above expression (6), and thepermissible range of the cold-water flow rate of the evaporator 66 canbe determined from the quantity of heat exchanged, Qe. The permissiblerange of the cold-water flow rate is set, for example, within plus orminus 20% of the cold-water flow rate calculated from the quantity ofheat exchanged, Qe.

If the cold-water flow rate of the evaporator 66 calculated using thecalculation method described in the first embodiment exceeds thepermissible range of the cold-water flow rate of the evaporator 66determined from the above expression (6), it is determined that, forexample, a differential pressure sensor provided in the evaporator 66has a fault. If such a fault in the sensor is detected, the controlpanel 74 may transmit the cold-water flow rate obtained from the aboveexpression (6) to facility-side equipment or may control theturbo-refrigerator 11 using this cold-water flow rate.

According to the second embodiment of the present invention, asdescribed above, the relational expression that holds for the motivepower consumption W of the turbo-compressor 60, the quantity of heatexchanged in the evaporator 66, Qe, and the quantity of heat exchangedin the condenser 62, Qc, is set at the control panel 74, and thepermissible range of the cold-water flow rate of the evaporator 66 isdetermined using this relational expression; if the cold-water flow ratecalculated on the basis of the measurement data from the differentialpressure sensors provided at the cold water outlet and inlet of theevaporator 66 exceeds the permissible range of the cold-water flow rate,a sensor fault is detected, thus allowing for rapid detection of thesensor fault. Furthermore, even if a sensor fault is detected, theoperation of the turbo-refrigerator 11 can be continued, and datatransmission to facility-side equipment can be continued by using thecold-water flow rate of the evaporator 66 obtained from the aboverelational expression (6).

In the turbo-refrigerator 11, in addition to the relational expressiongiven by the above expression (6), for example, the relationalexpression of the cold-water flow rate of the evaporator 66 holds alsofrom the head of the turbo-compressor 60 and the Q-H characteristics ofan inverter frequency and a reference frequency. Since a head Hcorresponding to the differential pressure between a condensed coolantpressure Pc and an evaporated coolant pressure Pe for the Q-Hcharacteristics of the compressor 60. Therefore, the volumetric flowrate of a coolant passing through the compressor 60 can be obtainedusing the Q-H characteristics. If we let Q1 be the volumetric flow rate,the weight flow rate Ge of the coolant flowing in the evaporator 66 canbe obtained using the following expression, where ρR is the density ofcoolant gas, and β is the ratio of the evaporator flow rate to thecompressor flow rate.

Ge=β·ρR·Q1

The motive power consumption W of the compressor 60 can be given by thefollowing expression, where Δh is a required compressor head, and ηc isa compressor efficiency.

W=Ge·Δh·ηc

Accordingly, the permissible range of the cold-water flow rate of theevaporator 66 may be determined on the basis of the Q-H characteristicsand the like, instead of the above expression (6), and a fault in thedifferential pressure sensors etc. may be detected.

REFERENCE SIGNS LIST

-   11 turbo-refrigerator-   60 turbo-compressor-   62 condenser-   66 evaporator-   70 inverter-   F2 flowmeter-   PEin, PEout differential pressure sensor-   Tout, Tin temperature sensor

1. A heat pump including a first heat exchanger that cools or heats aheating medium flowing from an external load, a second heat exchangerthat exchanges heat with outside air or cooling water, a coolantcirculation path through which a coolant is circulated between the firstheat exchanger and the second heat exchanger, and a turbo-compressorprovided in the coolant circulation path, the heat pump comprising: adifferential-pressure measuring part for measuring the differentialpressure between the inlet-side pressure and the outlet-side pressure ofthe heating medium in the first heat exchanger; and a control partstoring a loss factor of the first heat exchanger, for calculating theflow rate of the heating medium in the first heat exchanger on the basisof the loss factor and the differential pressure output from thedifferential-pressure measuring part, wherein the control part performscontrol using the flow rate of the heating medium and transmits the flowrate of the heating medium to facility-side equipment.
 2. The heat pumpaccording to claim 1, wherein the control part obtains a correction termdepending on the measurement delay time of the outlet-side pressureaccording to the amount of the heating medium held in the first heatexchanger and corrects the flow rate of the heating medium using thecorrection term.
 3. The heat pump according to claim 1, wherein thecontrol part obtains the permissible quantity of heat exchanged in thefirst heat exchanger by substituting the current motive powerconsumption of the turbo-compressor and the quantity of heat exchangedin the second heat exchanger into a relational expression expressing therelationship among the motive power consumption of the turbo-compressor,the quantity of heat exchanged in the first heat exchanger, and thequantity of heat exchanged in the second heat exchanger and determinesthe permissible range of the flow rate of the heating medium in thefirst heat exchanger from the permissible quantity of heat exchanged inthe first heat exchanger, wherein if the flow rate of the heating mediumdetermined by calculation exceeds the flow rate range of the heatingmedium, the control part determines the flow rate of the heating mediumon the basis of the flow rate range of the heating medium and transmitsthe value to the facility-side equipment.
 4. A method for calculatingthe heating-medium flow rate of a heat pump including a first heatexchanger that cools or heats a heating medium flowing from an externalload, a second heat exchanger that exchanges heat with outside air orcooling water, a coolant circulation path through which a coolant iscirculated between the first heat exchanger and the second heatexchanger, and a turbo-compressor provided in the coolant circulationpath, wherein a differential-pressure measuring part for measuring thedifferential pressure between an inlet-side pressure and an outlet-sidepressure are provided at an inlet and an outlet of the heating medium ofthe first heat exchanger, and the flow rate of the heating medium in thefirst heat exchanger is calculated on the basis of the loss factor ofthe first heat exchanger and the differential pressure output from thedifferential-pressure measuring part.